a. Field of Invention
The invention relates to a push-pull actuator for switches with a biased, longitudinally supported movable mushroom knob coupled to a plunger for actuating the switch contacts. The actuating plunger has selectively activated detent means both in the on and off positions.
b. Description of the Prior Art
In a known push-pull actuator (DE-GM 78 05 186), an operating detent slot is made sufficiently long that, as long as switching cannot take place by the force of a spring, a mechanical separation of the contacts can still be performed. Disengagement of the operating detent is accomplished by a separate key which only makes it possible to rotate the mushroom knob. In addition, a spherical element is used which is not secure and may be removed by force.
In another known push-pull actuator for key switches of the above-mentioned type (German Patent 30 02 069) the push-pull actuator may not be unintentionally defeated to interrupt the current by rotating the mushroom knob in the rest position. However interruption of the current may not be avoided in the presence of heavy vibrations.